Friction brake or clutch arrangement

ABSTRACT

A drum may be coupled to a wheel by means of friction shoes circumferentially distributed on the drum and mounted on carriers which may be pressed radially inward against an outer friction face of the wheel by an inflatable tube interposed between the carriers and the drum. Each carrier is guided by an axially elongated, square bar secured between two radial flanges of the drum and movably confined between radial guide walls of the carrier. The central portion of a plate spring having the shape of a wide V is mounted on each end of the bar, and the terminal spring portions engage an inner circumferential wall of the carrier to bias the friction shoe associated with the carrier away from the wheel. The springs prevent slipping engagement between the shoes and the friction face of the wheel when pressure fluid is released from the inflatable tube.

United States Patent 2,710,087 6/1955 Picard nucnon BRAKE 0R cw'rcuARRANGEMENT 6 Claims, 7 Drawing Figs.

US. Cl 192/79, l92/88 B, 188/366 Int. Cl ..Fl6d 11/06, Fl6d 25/04 Fieldat Search l92/79, 85 AT, 88 B, 107 T; 188/366 References Cited UNITEDSTATES PATENTS Primary ExaminerAllan D. Hermann Attorney-Kelman andBerman ABSTRACT: A drum may be coupled to a wheel by means of frictionshoes circumferentially distributed on the drum and mounted on carrierswhich may be pressed radially inward against an outer friction face ofthe wheel by an inflatable tube interposed between the carriers and thedrum. Each carrier is guided by an axially elongated, square bar securedbetween two radial flanges of the drum and movably confined betweenradial guide walls of the carrier. The central portion of a plate springhaving the shape of a wide V is mounted on each end of the bar, and theterminal spring portions engage an inner circumferential wall of thecarrier to bias the friction shoe associated with the carrier away fromthe wheel. The springs prevent slipping engagement between the shoes andthe friction face of the wheel when pressure fluid is released from theinflatable tube.

PATENTEnuuv 9 ISTI SHEET 1 [IF 2 INVENTOR fi/sukc MQ PATENTEUunv 9 IBYISHEET 2 [IF 2 o0 OEPDRu FD INVENTOR EI'SOIK! sasaharm W W awo/ Kar a 1FRICTION BRAKE OR CLUTCH ARRANGEMENT This invention relates to frictioncouplings, such as friction brakes or clutches, and particularly to amounting arrangement for friction shoes movably mounted on one couplingmember for engagement with a friction face on another coupling memberunder the urging of a fluid-pressure operated, inflatable member.

It is known to connect two coupling members having spacedly oppositefaces about a common axis by means of friction shoes mounted on one ofthe faces and driven into engagement with the face of the other memberby an inflatable ring of resilient or at least pliable material. When itis desired to disengage the two coupling members, fluid is released fromthe inflatable ring, and the resiliency of its material, atmosphericpressure, or both cause the ring to contract, thereby releasing thefriction shoes from the cooperating face.

If the shoes were firmly engaged with the friction face prior to releaseof the pressure fluid to transmit torque between the members, the shoesmay seize the friction face, not be released fully when the ring isotherwise ready to contract, and slip on the friction face, therebybeing heated and worn down prematurely.

An object of the invention is the provision of a brake or clutcharrangement in which the friction shoes move away from the engagedfriction face as soon as the pressure in the associated inflatable ringdrops below a predetermined value which may be higher than atmosphericpressure, and thereby to prevent slipping engagement between the shoesand the cooperating friction face, or to hold slipping to a minimum.

With this object and others in view, the invention provides an improvedcarrier for each friction shoe. The carrier has two walls which arecircumferential relative to the axis of the clutch or brake and areconnected in radially offset relationship to bound a casing, one of thewalls being adjacent a face of the one coupling member on which thecarrier is mounted, and the other wall being adjacent the friction faceof the other coupling member and carrying the friction shoe or element.An elongated bearing bar is circumferentially guided in the casing forradial movement between the two aforementioned walls and partly projectsfrom the casing. A projecting part of the bar is secured to thevaforementioned one coupling member. A yieldably resilient device isinterposed in the casing between the bar and the aforementioned one wallof the same in such a manner as to bias the casing radially away fromthe friction face of the other coupling member.

Other features, additional objects, and many of the attendant advantagesof this invention will readily be appreciated as the same becomes betterunderstood by reference to the following detailed description of apreferred embodiment when considered in connection with the appendeddrawing in which:

FIG. 1 shows a friction shoe and the associated carrier of the inventionin front elevation;

FIG. 2 illustrates the device of FIG. I in side elevational section onits median plane;

FIG. 3 is a fragmentary, front elevational view of a brake or clutch ofthe invention including carriers as shown in FIGS. 1 and 1;

FIG. 4 illustrates the apparatus of FIG. 3 in section on the line IV-IV;

FIG. 5 is a perspective view of a spring for the carrier of FIGS. 1 and2;

FIG. 6A shows the device of FIG. 5 in section corresponding to FIGS. 2and 4, but on a larger scale; and

FIG. 6B shows a modification of the device of FIG. 6A in a correspondingview.

Referring now to the drawing in detail, and initially to FIGS. 3 and 4,there is seen as much of an apparatus which may function as a clutch orbrake as is necessary for an understanding of this invention, and theapparatus will be described initially in its operation as a clutch.

The input member of the clutch is a wheel D which is mounted as aflywheel on the output shaft of a motor in a nonillustrated manner andmay be coupled to a drum or pulley R from which the torque of the motormay further be transmitted in a conventional manner, not illustrated andnot directly relevant to this invention, as by a belt trained over theouter circumference of the drum R. The rim of the wheel D has acylindrical, outer friction face which is spacedly enveloped by acoaxial, inner face of the drum R. Axially spaced, radial flanges l2, 13extend from the inner drum face toward the axis and have each acircumferential row of openings 14, 15, the openings 14 in the flange 12being axially aligned with respective openings 15 in the flange l3.

Cylindrical journals I0, 11 at the two longitudinal ends of an otherwisesquare bearing bar 16 are received in each pair of aligned openings. Thebars 16 are elements of respective carriers for friction shoes 5 withwhich this invention is more specifically concerned. The carriers aremounted on the drum R in equiangular, circumferenti y spacedrelationship as is partly evident from FIG. 3.

Each carrier, individually shown in FIGS. 1 and 2, has an outercircumferential wall 1 which is cylindrically arcuate about the commonaxis of the drum R and of the wheel D, and a similar inner wall 2, thewalls being connected in radially offset relationship by radial walls 3,4 so that the walls 1-4 bound a casing 9. The associated bar 16 is heldcircumferentially centered in the casing 9 by two guide walls 6, 7 whichare axially shorter than the walls 1-4 and connect the walls 1, 2 inslidable engagement with respective, opposite planar faces of the bar16.

The bar 16 is'biased toward the wall 2, and the casing 9 is therebybiased radially away from the wheel D by a'pair of identical platesprings 8 shown in greater detail in FIGS. 5 and 6A. Each spring is madeof an approximately T-shaped steel plate having two arms or terminalportions 17, 18 and a stem or central portion 19 which is approximatelysquare and has a central aperture 20. The plate is bent in such a mannerthat the two major surfaces 19a, 19b, (FIG. 6A) of the central portion19 extend in parallel planes intersecting the major surfaces l7a, 17b(FIG. I) of the terminal portions l7, 18 at an angle which differs froma right angle only by a very small acute angle a in the relaxedcondition of the spring seen in FIGS. 5 and 6A.

In the mounted condition of each spring, the aperture 20 movablyreceives one of the journals 10, 11 of the bearing bar 16, and thecentral portion 19 of the spring 8 is interposed between the associatedflange 12, 13 of the drum R and the shoulder 16a of the bar 16 betweenthe journal 10, 11 and the main central portion of the bar which issquare in cross section. The portion of the spring 8 which connects thewings or terminal portions l7, l8 abuts from above on the planar topface 16b of the bar 16. The terminal portions l7, 18 extend from thecentral portion 19 toward the wall I obliquely in a common radiallyoutward direction and in respective opposite circumferential directions,as is best seen in FIGS. 1 and 3.

The outer face of the wall 2 carries a friction shoe 5 cpposite thefriction face of the wheel D. A hollow ring or annular tube E of heatand oil resistant synthetic rubber is attached to the innercircumferential face of the drum R and is connected to a pump or othersource of pneumatic or hydraulic fluid through a control valve in amanner known in itself and not illustrated. In the position of theapparatus shown in FIGS. 3 and 4, the ring E is vented to the atmosphereor to a sump, and is compressed by the springs 8 which bias the casings9 radially outward against the ring. The friction shoes 5 are radiallyspaced from the friction face of the wheel D, and the clutch isdisengaged. When the ring E is inflated with sufficient pressure, itdrives the carriers radially inward against the joint restraint of thesprings 8 to engage the several friction shoes 5 with the wheel D sothat torque may be transmitted between the nonillustrated motor andbelt. When the ring E is again deflated, the springs 8 promptly lift theshoes 5 from the wheel D and prevent slipping contact between the wheeland the shoes for any significant length of time. The shoes remain cooland wear only slowly.

The apparatus described with reference to FIGS. 1 to 6A is capable ofmany modifications. When the springs 8 on the bar 16 are set between theflanges 12, 13, the central portions 19 are resiliently deflected toreduce the magnitude of the angle a, as is evident from H6. 4. Thespring portion 19 abuts against the shoulder at the inner end of ajournal 10, 11 and against the opposite face of the associated flangel2, 13 to keep the bar 16 in a fixed axial position between the twoflanges. Some tilting movement of the journals 10, 11 in the openingsl4, 15 of the flanges l2, 13 is possible to compensate for uneveninflation of the tube E or uneven wear of a shoe 5, but the bar 16 issecured against all displacement relative to the flanges.

The same result is achieved with a plate spring partly shows in FIG. 68having a modified central portion 19 whose aperture 20 is surrounded byan annular offset portion 21 of the spring metal which functions in themanner of a cup spring to centerthe bar 16 between the flanges l2, 13.

Other modifications and variations will readily suggest themselves tothose skilled in the art. While the illustrated apparatus has beendescribed in its operation as a clutch capable of transmitting torquefrom a motor fastened to the wheel D to a load connected to the drum orpulley R, it can operate as a brake when the drum R is held stationary,and the functions of the wheel D and the drum R are interchangeable.Also, the ring E and friction shoes with the associated carriers may bemounted on the wheel D instead of the drum R in a manner too obvious torequire detailed description or pictorial representation.

lt should be understood, therefore, that the foregoing disclosurerelates only to preferred embodiments of the invention, and that it isintended to cover all changes and modifications of the example of theinvention herein chosen for the purpose of the disclosure which do notconstitute departures from the spirit and scope of the invention setforth in the appended claims.

What is claimed is:

l. in a brake or clutch arrangement including i. a first coupling membermounted for rotation about an axis and having a face extending saidaxis;

ii. a second coupling member having a face extending about said axisspacedly opposite said face of said first member;

iii. a plurality of carriers secured on one of said members againstangular movement relative to said one member about said axis;

iv. fluid-operated pressure means interposed between said face of saidone member and each of said carriers for moving said carrier toward saidface of the other member; and

v. a friction element mounted on each carrier for engagement with saidface of the other member upon said moving of the carriers, theimprovement in each carrier which comprises:

a. two walls circumferential relative to said axis and connected inradially offset relationship to bound a casing, one of said walls beingadjacent said face of said one member and the other wall being adjacentsaid face of the other member and carrying friction element;

b. an elongated bearing bar circumferentially guided in said for radialmovement between said walls and partly projecting from said casing, aprojecting part said one member and the other wall being adjacent saidface of the other member and carrying said friction element;

b. an elongated bearing bar circumferentially guided in said casing forradial movement between said walls and partly projecting from saidcasing, a projecting part of said bar being secured to said one member;and c. yieldably resilient means interposed in said casing between saidbar and said one wall for biasing said casing radially away from saidface of the other member,

1. said yieldably resilient means including a plate spring having acentral portion mounted on said bearing bar and two terminal portionsengaging said one wall,

2. said plate spring having two opposite major surfaces,

3. the major surfaces of said central portion of the plate springextending in respective parallel planes transverse to the major surfacesof said terminal portions,

4. said central portion being apertured and receiving said bearing barin the aperture thereof.

2. In an arrangement as set forth in claim 1, said bearing bar having aplanar face extending in the direction of said movement of the bar, andsaid casing including a guide wall extending between saidcircumferential walls and slidably engaging said planar face during w'dmovement of the bar.

3. in an arrangement as set forth in claim 2, said projecting part beingsecured to said one member for pivotal movement about a pivot axisparallel to said axis of said first member.

4. In an arrangement as set forth in claim 1, said terminal portionsextending from said central portion toward said one wall in a radialdirection and in opposite respective circumferential directions.

5. in an arrangement as set forth in claim 4, said one member beingformed with a radial flange, having an opening, said part of the bearingbar being received in said opening, said bearing bar being formed with ashoulder adjacent said part thereof, and said central portion beinginterposed between said shoulder and said flange for longitudinallysecuring said bearing bar relative to said one member.

6. ln an arrangement as set forth in claim 5, said central portionresiliently urging said shoulder away from said flange, respectivespaced parts of said central portion abuttingly engaging said shoulderand said flange.

1. In a brake or clutch arrangement including i. a first coupling membermounted for rotation about an axis and having a face exteNding aboutsaid axis; ii. a second coupling member having a face extending aboutsaid axis spacedly opposite said face of said first member; iii. aplurality of carriers secured on one of said members against angularmovement relative to said one member about said axis; iv. fluid-operatedpressure means interposed between said face of said one member and eachof said carriers for moving said carrier toward said face of the othermember; and v. a friction element mounted on each carrier for engagementwith said face of the other member upon said moving of the carriers, theimprovement in each carrier which comprises: a. two wallscircumferential relative to said axis and connected in radially offsetrelationship to bound a casing, one of said walls being adjacent saidface of said one member and the other wall being adjacent said face ofthe other member and carrying friction element; b. an elongated bearingbar circumferentially guided in said for radial movement between saidwalls and partly projecting from said casing, a projecting part said onemember and the other wall being adjacent said face of the other memberand carrying said friction element; b. an elongated bearing barcircumferentially guided in said casing for radial movement between saidwalls and partly projecting from said casing, a projecting part of saidbar being secured to said one member; and c. yieldably resilient meansinterposed in said casing between said bar and said one wall for biasingsaid casing radially away from said face of the other member,
 1. saidyieldably resilient means including a plate spring having a centralportion mounted on said bearing bar and two terminal portions engagingsaid one wall,
 2. said plate spring having two opposite major surfaces,3. the major surfaces of said central portion of the plate springextending in respective parallel planes transverse to the major surfacesof said terminal portions,
 4. said central portion being apertured andreceiving said bearing bar in the aperture thereof.
 2. said plate springhaving two opposite major surfaces,
 2. In an arrangement as set forth inclaim 1, said bearing bar having a planar face extending in thedirection of said movement of the bar, and said casing including a guidewall extending between said circumferential walls and slidably engagingsaid planar face during said movement of the bar.
 3. In an arrangementas set forth in claim 2, said projecting part being secured to said onemember for pivotal movement about a pivot axis parallel to said axis ofsaid first member.
 3. the major surfaces of said central portion of theplate spring extending in respective parallel planes transverse to themajor surfaces of said terminal portions,
 4. said central portion beingapertured and receiving said bearing bar in the aperture thereof.
 4. Inan arrangement as set forth in claim 1, said terminal portions extendingfrom said central portion toward said one wall in a radial direction andin opposite respective circumferential directions.
 5. In an arrangementas set forth in claim 4, said one member being formed with a radialflange, having an opening, said part of the bearing bar being receivedin said opening, said bearing bar being formed with a shoulder adjacentsaid part thereof, and said central portion being interposed betweensaid shoulder and said flange for longitudinally securing said bearingbar relative to said one member.
 6. In an arrangement as set forth inclaim 5, said central portion resiliently urging said shoulder away fromsaid flange, respective spaced parts of said central portion abuttinglyengaging said shoulder and said flange.